At 05:41 PM 1/9/2002 +0000, Stephen Casey wrote: >Check out > >www.russandrews.com > >I have learned a huge amount from Mr. Andrews. Mains voltage variation of >10% can have a +/- 1% effect on playback speed of CD's. Amazing, don'tcha >think?
It would be amazing, yes. But I don't believe it at all. Perhaps some CD player somewhere was not crystal-controlled. But I also doubt that anyone who did not have perfect pitch would be able to detect a 1% variation in playback speed, and it might be difficult with perfect pitch (unless the CD output was being compared with some standard). > Oh yes, and over three thousand UK pounds for speaker cables - they >must be very good! He also sells woven earth wire, to rewire your home with. >Could make a big difference. In the weight of your wallet! I looked at one of his publications, The Power and the Glory. From that PDF: "The mains voltage has a surprising effect on the performance of a CD player. The motor speed is voltage controlled, not frequency controlled with a crystal reference as most people would expect." This person doesn't expect motor speed to be crystal-controlled! I'm not an audio engineer and I have never seen a CD player design, but a CD player is simply a device for reading data, I'd then expect that the data is loaded into a FIFO memory and from there to a DAC; the rate of data transfer to the DAC would be frequency-controlled, so motor speed is irrelevant, as long as the drive can read data fast enough to keep the FIFO from running out of data. Someone correct me if I'm wrong! How did Mr. Andrews conclude that line voltage affects CD speed? *Subjectively*. "To test the effect of mains voltage variation, Paul Holden of ATMC (a transformer manufacturer) made a special transformer with voltage tappings at 0.9, full mains, and 1.1 mains voltage. [Apparently they never heard of a Variac.} These small changes were enough to change the tempo of the music on a CD by clearly observable amounts. Paul plays drums, so the changes in tempo were very obvious to him. We estimated that each '0.1' voltage change in either direction caused a 1% speed change. "(I must emphasize that these were subjective listening assessments as we were unable to measure the speed of the CD itself.)" He's not kidding they were subjective! I'm a drummer also. 1% would be hard to hear, again, unless I could beat it against something else. But it would be easy to measure much smaller speed changes in a CD. All it would take would be a watch with a second hand! Duh! Anyone else here like to read Bob Pease? As I recall he has discussed this speaker cable thing. The people who promote Monster cable are not big on double-blind testing.... [EMAIL PROTECTED] Abdulrahman Lomax Easthampton, Massachusetts USA * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[email protected] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
